A PN junction diode can be used as a rectifier by taking advantage of its asymmetric conduction properties - it conducts easily in the forward bias direction but blocks conduction in the reverse bias direction. There are three main rectifier configurations: half wave which only uses the positive half of the AC cycle, center-tapped full wave which uses both halves but requires a center tap, and full wave bridge which uses both halves without a center tap and is the most efficient design. The mathematical analysis shows that the output current follows the input voltage during conduction periods but is zero when the diode is reverse biased.

1. Pn junction as a rectifier
●
The process by which ac is converted to dc is called rectification.
●
The diode offers low resistance during forward bias and high resistance during
reverse bias
Three types of configuration of
diodes
✗
Half wave rectifier
✗
Centre tapped full wave
rectifier
✗
Full wave bridge rectifier

2. Half wave rectifier
●
Only positive half cycle obtained
●
Output is a Pulsating dc

3. During the positive half cycle of ac the
diode is forward biased and conducts for
all voltages above knee voltage.
During negative half cycle of ac the diode
is reverse biased and will not conduct at
all.
Mathematical analysis
The input voltage applied , Vi
=Vm
sinωt
The instantaneous output
current through the load
resistance RL
IL
= Im
sinωt (0-π)
IL
= 0 (π-2π)
The peak value of the current Im
=
Vm
RL +Rf
Working principle

6. Not so efficient
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